Invasive infection caused by a novel Emmonsia species in a renal transplant patient.
Case Summary A 39 year old Asian male with a background history of ischemic heart disease, type II diabetes and a cadaveric renal transplant (3 years previously) presented to hospital with fever accompanied by throat and neck pain and dysphagia. His medications included prednisone and mycophenolate. He was started on broad-spectrum antibiotics to cover for suspected oropharyngeal infection and atypical pneumonia. Chest X-ray showed fine bilateral nodules, and chest CT revealed diffuse small parenchymal nodules,consolidation in the left upper lobe and a single enlarged mediastinal lymph node. Fluconazole was started after the upper airway was assessed by ENT and found to be clear except for a few white patches. He remained febrile and developed generalized myalagias and arthralgias, prompting collection of blood cultures in Bactec Myco-F-lytic bottles on day 5 post-admission. Two days later, a bronchoscopy was performed, revealing white patches that had a â€œfungal appearanceâ€ in the trachea. Bronchoscopy specimens were reported to be positive for Pneumocystis carinii on fluorescent staining, prompting an antibiotic change. Two weeks after they had been drawn, the Myco-F-lytic blood cultures were reported to be positive for yeast-like cells and hyphae by Gram stain and subculture yielded a fungus . Blood culture was repeated, and the patient was started on amphotericin B lipid complex 5 mg/kg/day. The repeat blood culture and the fungal culture from the bronchoscopy also grew the same organism after approximately 14 days of incubation. The patientâ€™s condition gradually improved and his fever resolved after 12 days of antifungal therapy. Three sets of repeat blood cultures drawn after antifungal therapy was initiated were negative. The patient received a three week course of amphotericin B lipid complex, and he was discharged from hospital seven weeks after his admission. The organism The fungal isolate had both yeast cells and filaments and was difficult to identify in the hospital laboratory using conventional methods. PCR/sequencing of the ITS2 region showed the closest matches to be Emmonsia parva (271/271 bases = 100% match) and E. crescens (95%). Because the isolate appeared to be different from previous descriptions of these organisms, it was referred to the University of Alberta Microfungus Collection and Herbarium for further identification The isolate demonstrated microscopic morphology typical of an Emmonsia species in forming one to three small oval conidia at the ends of narrow, often slightly swollen stalks, but it was unusual in demonstrating a yeast stage when grown at 35 C. To assess the relationship with other species of Emmonsia, large subunit ribosomal and complete ITS1-ITS2 region sequences were obtained and analyzed phylogenetically. Results demonstrated that the case isolate was identical to an isolate obtained previously from Saskatchewan, Canada, and that these two isolates represent a species different from E. crescens, E. parva and E. pasteuriana.
Full conference title:
15th Annual Focus on Fungal Infections